Currently, the capacitive touch screen for its high reliability and durability is widely used in various types of electronic equipment. FIG. 1 shows a typical structure of the self capacitive touch screen.
as shown in FIG. 1, self capacitive touch screen generally includes: a cover plate with surface hardness, a conductive electrode for inducting user-triggered state and a bonding layer bonded between the cover plate and the conductive electrode; wherein the conductive electrode with monolayer or multilayer film structure is an transverse or longitudinal electrode array made of conductive material on the surface of the glass or thin film materials, the conductive electrode form a self capacitor Cp between the conductive electrode and ground. Its working principle is: when a finger touch the cover plate, the body is equivalent to the earth, the finger and the conductive electrode form a capacitor CF, the capacitor Cf and the self capacitor Cp are in parallel, so the induction capacitor in the corresponding channel of the conductive electrode increases; capacitive induction chip gathering the induction capacitor of each channel on real-time, when the change of the induction capacitor relative to the self capacitor Cp is greater than the touch threshold value, it is considered that there is a touch, and then calculate the touch point coordinates according to the proportionate relationships of the change of each channel of the touch point area, and then output the touch point coordinates to the main processor, so the processor execute touch application.
However, in practical applications, the self capacitive touch screen has certain deformation due to pressure, so the distance between the conductive electrode and the ground are reduced. The change of the self capacitor Cp caused by the deformation is ΔCP, the change of the induction capacitor relative to the self capacitor Cp detected by the capacitive induction chip is ΔCp+Cf. The prior art ignored the influence of the change of the self capacitor ΔCP on the identification result to the touch point, while for non-touch area, if the change ΔCP is larger than the touch threshold value, the capacitive induction chip will identify there is a touch fake point in the area, which may result in inaccurate identification of the touch points, affect the proper implementation of the touch applications and reduce the user experience.